Expendable phase change detector device



June ll, 1968 R. J. HANCE EXPENDABLE PHASE CHANGE DETECTOR DEVICE 2Sheets-Sheet Original Filed June 7, 1963 June 1l, 1968 R 14 HANCE Re.26,409

EXPENDABLE PHASE CHANGE DETECTGR DEVICE Original Filed June 7, 1963 2Sheets-Sheet 2 F ig.3

United States Patent O 26,409 EXPENDABLE PHASE CHANGE DETECTOR DEVICERichard 5. Hance, Philadelphia, Pa., assigner to Leeds &

Nortlirup Company, a corporation of Pennsylvania Griginal No. 3,267,732,dated Aug. 23, 1966, Ser. No.

286.312, .lune 7, 1963, which is a continuation-impart of Scr. No.238,966. Nov. 20, 1962. Application for reissue Mar. 2l), 1967, Ser. No.628.5l4

17 Claims. (Cl. 73-359) Matter enclosed in heavy brackets appears in theoriginal patent but iorms no part of this reissue specilication; matterprinted in italics indicates the additions made by reissue.

ABSTRACT 0F TEE DISCLOSURE Aft expendable pltnsc Change prcfabl'icnrcddetector dcvice for use in Obtaining a Cooling curve o] molten mate rialoutside of the melting furnace. The device includes well structurehaving a relatively small volume and open at the top thereof to receiveand retain molten material placed therein. Temperonde-sensing means issupported within the well structure and is provided with electricalConductors extending tllrottglz the 'vvnll and Corrieri by nu extensionon the well structure. The extension includes means for holding theelectrico! conductors in yxell p0si tion of predetermined polarity forengagement with associated Contact structures of corresponding polarityin connecting the temperature sensing means to a measuring circuit.

rthis is a continuation-in-part of the parent application, Serial No.238,906, filed November 20, 1962, now abandoned.

This invention relates to a device for obtaining a cooling curve ofmolten materials and has for an object the provision of an expendablephase change detector partielllarly useful in industrial applicationswhere phase change detection can be used as a quality control guide orfor research purposes.

The present invention is particularly applicable to obtaining a coolingcurve of molten metals such as cast iron or steel. For example, in themolding of gray iron castings, a study ol solidincation characteristicspermits the determination of the carbon equivalent value of cast iron.The mechanical properties of gray iron depend to a substantial extent onits carbon equivalent value. Whether the iron solidifies gray as desiredor as white iron will depend upon the carbon equivalent value. Onemethod of determining the composition and hardness of iron is bychemical analysis as described in the article entitled, Rapid ControlTest for Carbon Equivalent, by D. E. Krause in the May i962 issue of"Foundry. This article points out the deficiency in the chemicalanalysis results and describes a carbon equivalent test based on thcmcasurenlcnt ol thermal arrests or phase change temperatures as a sampleof molten cast iron freezes outside of the melting furnace. The phasechange temperatures correspond to initial separation of austcnite fromthe melt liquid (liquidus) and final solidication of the remainingliquid of entectic composition (solidus). Such tests were performed byusing sand core molds each comprising a pair of half-sections withseparate thermocouples which required assembly by the user and clampingof the molds during use. Such sand molds are of relatively complicatedconstruction and include a substantially U-shaped chamber with an upperreservoir acting as an overflow cavity that permits the hist metalpoured into the mold to be used for prchcating the thermocouple and sandfrom which the mold is constructed.

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While the aforementioned sand molds satisfactory results, neverthelessthey have left something to be desired. The production of sand molds istime consuming and requires a certain amount of labor and care wheninserting the separate thcrmocouple assembly. Additionally, particularcare must be taken to insure connection of the thermocouple wires withthe corrcct polarity. The present invention avoids the foregoingdifficulties by providing a factory made or prefabricalcd cX- pcndableunit including as integral parts thereof a thermocouple with a reservoiror well structure adapted to bc Supported with the open end of the wellstructure disposed upwardly for receiving and retaining a moltenmaterial therein. The unit is of relatively low cost and is constructedas a completely assembled unit ready to be plugged in for use in atemperature measuring circuit.

ln accordance with one aspect of the invention, there is provided anexpendable phase change detector device for obtaining a cooling curve ofmolten material outside ol the melting furnace comprising a body memberadapted for vertical disposition and a temperature sensing meanspermanently sealed to and supported by the body member s0 as to becomean integral part thereof. The temperature sensing means extends from oneend of the body member a predetermined distance and has electricalconductors extending through at least part of the body member toward theopposite end thereof and forming plugfin contact structure accessiblefrom the opposite end of the body member. Tubular wall structure havingan open end is carried by the body member and together therewith formsan open end liquid-tight well around the temperature sensing means sothat upon vertical disposition of the structure the well is adapted toreceive and retain a quantity of molten material. The tubular wallstructure has a length substantially greater than the predetermineddistance which the temperature sensing means extends beyond the end ofthe body member which forms the bottom of the well. The tubular wallstructure and body mcmbcr are comprised of material having thecharacteristic of rctarding the cooling of a sample of molten materialto be received in the well at a rate that allows detection of thethermal arrests in accordance with the rate of response of thetemperature sensing means. The depth of the well is related to thepredetermined distance th'e temperature sensing means extends beyond thebottom of the well so as to maintain the temperature sensing meanswithin the sample of molten material in the well and below any shrinkagecavity formed in the sample during cooling.

Where the body is constructed separately from the tubular wallstructure, the outer surface of the body which is adapted to engage theinner surface of the tubular wall structure is provided with a taperwhich tapers from a large cross-section to a smaller cross-section, withthe smaller cross-section being at the end of the body member from whichthe temperature sensing means extends to provide a tapered seat for thetubular wall structure.

For further objects and advantages thereof and for a more detaileddescription of the invention, reference is to be had to the followingdescription taken in conjunction with the accompanying drawings inwhich:

FIG. l is a perspective view of a test stand and plug-in detectorembodying the invention;

FIG. 2 is an exploded sectional view on an enlarged scale of a preferredform of well structure and electrical connections; and

FIG. 3 is a sectional view of a modification of the plugin detector.

Referring to FIG. 1, there is shown an expendable phase change detectordevice 10 supported at its lower end in a test stand 1l. The test standincludes a base 12 which has been illustrated as a pipe [lange connectedby have produced a threaded nipple 13 to a conduit box 14. The conduitbox 14 is provided with a laterally extending conduit 15, the outer endof which is provided with a lug type electrical connector 16. TheConnector 16 has connected thereto lead wires 22, 23, FIG. 2, whichextend through the conduit and upwardly through the conduit box 14 intothe fitting 17 which contains an electrical connector element thedetails of which are shown in FIG. 2.

As may be seen in FIG. 2, the fitting 17 is provided with an insulator18 retained in the fitting 17 by a pin 19. The insulator 18 may be madeof any suitable electrical insulating material such for example asceramic and is provided with a pair of spaced contact rings 20 and 21.One of the lead wires 22 is connected to ring 20 and the other lead wire23 is connected to ring 21.

The device 10 as shown in FIG. 2 includes a body member 25 of ceramichaving an opening therethrough within a counterbore-like cavity at 27 ofa predetermined depth for positioning the temperature sensing means 28.The temperature sensing means 28 has been illustrated as a thermocouplecomprising 22 gauge Chromel-Alumel wires 28a, 28h having ends twistedtogether at one end to form a heat responsive portion 28e with the freeends inserted in a two hole insulator 29. The insulator tube 29 may bemade of any suitable material such, for example, as fused quartz. Theheat responsive portion 28e extends beyond the end of the insulator 29and the wires of the thermocouple 28 are sealed within the insulator 29with a refractory cement such as Alundum cement 30. The lower end of theinsulator tube 29 is seated in the cavity 27 and is [seated] sealed inplace by Alundum or other suitable refractory cement 31. The lower endsof the thermocouple wires 28a and 28h extend through the hole in thebody 25 and into a tubular insulator 32 which is received within acounterbore-like cavity 33 at the lower end of the body 25. The tubularmember 32 is made of hard paper or other equivalent electricalinsulating material and is provided with notches 32a and 32b forreceiving the ends of the respective thermocouple wires 28a and 2Sbwhich are bent back to form electrical contacts. The notches 32a and 32hare axially displaced along the length of tube 32 a distancecorresponding to the spacing of the cooperating contact rings 21 and 20on the test stand 11. This construction insures that the proper polarityof the thermocouple connections with a measuring instrument will bemaintained regardless of the orientation of the device 10. It is to beunderstood that the rings 20 and 21 and wires 22 and 23 will be made outof the same material as the thermocouple wires 28a and 28h. However, aswill be understood by those skilled in the tart, when the thermocouplewires are of noble metal, compensating lead wire materials may be used.

The body member 25 has been illustrated with the lower end thereof beingof larger diameter than the upper end so as to provide a tapered seat25a for receiving the lower end of the tubular wall structure 34. Thetubular wall structure 34 and body 25 cooperate to form a liquidtightwell around the heat responsive portion 28e of temperature sensing means28. By providing the body 25 with the aforementioned taper, thecylindrical Wall 34 is pressed onto the body 25 sufiiciently tight toprovide a leak-proof well. The pressed fit of the tube 34 on body 25 issufficiently tight to retain the tube in place in a manner similar toforming the tube integral with the body 25.

The tube 34 in a presently preferred form of the invention comprises aninner thin walled circular steel tube 34a. The outer surface of thesteel tube 34a is covered with heat insulating material 34h such, forexample, as ceramic impregnated asbestos tape.

In one embodiment of the invention, the steel tube 34a had an internaldiameter of `about 11/2 inches, a wall thickness of .012 inch and wascovered with a double layer of ceramic saturated asbestos tapeapproximately 0.1 inch thick spirally wound thereon. The metal tube wasfirst coated with ceramic cement.

The length of the tube 34 is related to the distance which the heatresponsive portion 28e extends beyond the end face of the body member 25so as to produce a depth of well for receiving the sample of moltenmetal or other molten material which will maintain the temperatureresponsive portion 28e within the sample and below any shrinkage cavityformed `by the sample during cooling thereof. In an embodimentparticularly suited for obtaining the cooling curve of cast iron, a4-inch tube was pressed onto a body 25 in `a manner providingapproximately a 3l/z inch deep reservoir for the molten metalsurrounding the heat sensitive portion 28C. The inside diameter of themetal tube 34a was approximately 1.62 inches and the temperatureresponsive portion 28e was positioned about 2l/s inch below the open endof the well. Thus, it will be seen that the well structure is relativelysmall having a cubical content of the order of less than about ten cubicinches and that the temperature responsive portion projects asubstantial distance above the `bottom of the well, ie., approximatelyonethird of the distance between the bottom and top of the well.

While the embodiment illustrated in FIG. 2 shows a device having aseparable tube 34, it is to be understood that the tube 34 may be formedintegral with the body member 25 with both the body 25 and tube 34 beingof ceramic or equivalent material. A thin metal liner 34a may beinserted within the outer ceramic tube. It is further to be understoodthat the separable tube 34 of FIG. 2 may either be assembled at thepoint of manufacture or at the point of use as desired.

Referring to FIG. 3 there is shown a modification of the expendablephase change detector device. The detector device 10a shown in FIG. 3 isa cupshaped structure formed into a monolithic mass of Sand and a resinbinder. The cup-shaped structure 40 includes a bottom 40a and a sidewall 40h which cooperate to provide Well structure for receiving themolten material. The outer surface of the bottom 40a is provided with anextension 40e which is adapted to support the electrical contacts forthe thermocouple. It has been found that the wall portions 40a, 40h tand40e lof the well structure 40 may be relatively thin and still provideadequate strength for receiving the molten metal mass. ln view of this,the well structure 40 may be produced by shell molding. In shell moldinga thin shell mold is produced by covering a hot metal pattern or diewith a mixture of sand and a resin binder. The resin binder is heatsetting such as a phenol-formaldehyde resin binder. The thin shell moldmay be produced in various ways, one of which is by blowing `the sundand resin into the die cavity and the thin mold so formed is thencapable of being hardened completely by heating for approximately threeminutes at 300 C. After baking, the thin sand shell is then lifted fromthe pattern or die. While the well structure 40 is formed of sand,nevertheless, it is a self-supporting structure and does not needadditional supports or clamps for the walls while receiving the moltenmetal. This is an advantage `of the shell molding process over theordinary core, sand molding technique which when combined with otherfeatures of applicants invention provides a `low cost plug-in expendableunit. For further reference as to the shell molding process, referencemay be had to the publication Tool and Manufacturing Engineering, volume46, January 1961, and the references listed on page 116.

The temperature sensing means 28 shown in FIG. 3 is essentially the sameas that shown in FIG. 2. It has been illustrated as a thermocouplecomprising Chromel-Alumel wires 28a, 28h having ends twisted together atone end to form a heat responsive portion 28e with the free ends`inserted in the two-hole insulator 29. The heat responsive portion 28cextends beyond the end of `the insulator 29 and the wires of thethermocouple 28 are sealed within the insulator 29 with a refractorycement 30. The lower end of the insulator tube 29 extends into thebottom 40a of the well structure 4l) and preferably is sealed in placeby Alundum or other suitable refractory cement 31. The lower end of theltherrnocouple wires 28a and 28h extend through the bottom 40a and intothe tubular portion 40e. Tubular portion 40e is provided with notches onopposite sides for receiving the ends of the respective thermocouplewires 28a and 28h which are bent back to form electrical contracts. Theelectrical contacts are .adapted to engage the respective Contact rings21 and 20 on the test stand 11, the upper end of which is shown incross-section in FlG. 2.

By molding the bottom 40a integral with the side wall 4Gb, there isavoided the possibility of any leakage between thc two. Additionally, bymolding the contact support 40e integral with the bottom 40a the numberof `assembly steps have been minimized. The Weight 0f the device 10ashown in is an advantage from a shipping standpoint. It has been found`that an unsupported monolithic wall of sand and rcsin binder having athickness in the order 0f 0.1 inch is adequate to support the moltenmaterial as it is poured into the well structure and additionally for atime interval long enough for an outer metal shcll to form before themold beings to disintegrate.

lt is to be understood that the invention is not limited to the formswhich have been described and illustrated herein and that other formsthereof may be constructed within the scope of the appended claims.

What is claimed is:

l. An expendable phase change detector device adapted for verticaldisposition for use in obtaining a cooling curve of molten materialoutside of the melting furnace comprising a body member, temperaturesensing means supported by said body member and extending from orc endof said body member a predetermined distance, said temperature sensingmeans having electrical conductor-s extending through at least part ofsaid body member toward the opposite end thereof and forming plug-inelectrical contact structure accessible from said opposite end of said`body member, tubular wall structure carried by said body member at saidone end thereof and together therewith forming an open end liquid-tightwell around said temperature sensing means so that upon verticaldisposition of the device said open end of said well is adapted toreceive and said well retain a quantity of molten material, said tubularwall structure having a length substantially greater than saidpredetermined distance which said temperature sensing means extendsbeyond said one end of said body member which forms the bottom of saidwell, said tubular wall structure and body member being comprised ofmaterial having the characteristic of retarding the cooling of a sampleof the molten material to be received in said well, the depth of saidwell being related to said predetermined distance said temperaturesensing means [extend] extends beyond said bottom of said well so as tomaintain said temperature sensing means within the sample of moltenmaterial in said well and below any shrinkage cavity formed in thesample during cooling.

2. An expendable phase charge detector device for use in obtaining acooling curve of molten material according to claim l wherein said bodymember is formed intcgral with said tubular wall structure.

3. An expendable phase change detector device for use in obtaining acooling curve of molten material according to claim 1 wherein said bodymember is iormed integral with said tubular wall structure into aself-supporting structure from a mixture of sand and a heat settingresin.

4. An expendable phase change detector device for use in obtaining thecooling curve of molten material according to claim 1 wherein saidtemperature sensing FIG. 3 is relatively small and this ifi meanscomprises a thermocouple, tion of which is disposed along member.

S. An expendable phase change detector device for use in obtaining acooling curve of molten material ac cording to claim 1 wherein said bodymember and said tubular wall structure are each comprised of ceramicmaterial.

6. An expandable phase change detector device for use in obtaining acooling curve of molten material according to claim 5 wherein saidtubular wail structure or ceramic material is provided with a thin metalliner.

7. An expendable phase change detector device adapted for verticaldisposition for use in obtaining a cooling curve ol molten materialoutside of the melting furnace comprising a body lmember, temperaturesensing means supported by said body member and having a heat responsiveportion extending beyond one end of said body member a predetermineddistance, said temperature sensing means having electrical conductorsextending through said body member toward the opposite end thereof andforming electrical contact structure accessible from said opposite endof said body member, tubular wall structure carried by said body memberat said one end thereof and together therewith forming an open endliquid-tight well around said temperature sensing means so that uponvertical disposition of thc device said open end of said well is adaptedto receive and said well retain a quantity of `molten material. saidtubular wall structure having a length substantially greater than saidpredetermined distance which said heat responsive portion of siidtemperature sensing means extends beyond said one end of said bodymember which forms the bottom of said well` said predetermined distancebeing approximately onethird the distance between the bottom and openend top of said well so as to locate slid heat responsive portion ofsaid temperature sensing means a substantal distance from the bottom ofsaid well, said tubular wail structure comprising a thin metal liner,the outer surface of which is covered with material having thecharacteristic of retarding the cooling of a sample of the rnoltenmaterial to be received in said well structure, the depth of said wellstructure being related to said predetermined distance said temperaturesensing means extends beyond said bottom of said well so as to maintainsaid temperature sensing means within the sample of molten material insaid well and below any shrinkage cavity formed in the sample duringcooling.

8. An expendable phase change detector device for use in obtaining acooling curve of molten material cutslde of the melting furnacecomprising a body member, temperature sensing means protruding from aface 0f said body member with the heat-responsive portion thereofdisposed in spaced relation to said face, electrical conductors inelectrical connection with said temperature sensing means passingthrough at least a portion of said body member and terminating inelectrical contact portion, and said body member having wallstructure[.] adjacent said face which tapers gradually from a largecrosssection to a smaller cross-section with the smaller crosssectionbeing at the end of said body member nearest said tace from which saidtemperature sensing means protrudes to provide a tapered seat, and anopen-ended tube seated on slid tapered seat in liquid-tight engagementto provide a receptacle for the molten material.

9. An expendable phase change detector device :for use in obtaining acooling curve of molten material outside of the melting furnacecomprising well structure adapted for vertical disposition to hold asample of molten material and having a relatively small cubical contentof the order of less than about ten cubic inches with the wall structureoi said well structure including material tending to retard cooling of asample of molten ,material to be received in said well structure, heatsensing means supported substantially axially of said well structure ata the heat-receiving juncthe axis of said body point below any shrinkagecavity formed in the sample during cooling thereof, said wall structuretending to retard cooling at a rate that allows detection of the thermalarrests with said associated heat sensing means having a predeterminedspeed of response, and an electrical contact supporting member rigidlysupported by the wall structure of said well structure with electricalconductors connected to said heat sensing means secured to said contactsupporting member in a manner to form plug-in electrical contact meansfor connecting said device to a measuring circuit.

10. An expendable phase change prefallricated detector device for use inobtaining a cooling curve of molten material outside of the meltingfurnace comprising7 Well structure of material and shape which retardsthe rate of cooling of a molten material poured therein, temperaturesensing means supported `from a wall of said well structure andextending a predetermined distance therefrom for disposition of aheat-responsive portion thereof substantially on the longitudinal axisof said well structure and spaced from the walls thereof, saidtemperature sensing means being permanently sealed to said wellstructure so as to become an integral part thereof, said well structuretending to retard cooling at a rate that allows detection of the thermalarrests in accordance with the rate of response of the temperaturesensing means, said temperature sensing means having electricalconductors extending through said wall of said well and terminating inelectrical Contact structures included in plug-in electrical contactstructure accessible exteriorly of said well and carried thereby, saidplug-in electrical Contact structure also including an extension carriedby ond projecting exteriorly of said well adjacent the location wheresaid electrical conductors extend through said wall, said extensionhaving means for holding said contact strnctures in jred position ofpredetermined polarity for engagement with associated Contact structuresof corresponding polarity in connecting said temperature sensing meansto a measuring circuit, and said wcll structure having a length suchthat said heat-responsive portion of said temperature sensing means isalways completely surrounded by the molten material placed in said welland below any shrinkage cavity formed in said material upon cooling.

11. An expendable phase change detector device for use in obtaining acooling curve of molten material according to claim 10 wherein saidmaterial from which said well structure is formed comprises a mixture ofsand and a binder.

12. An expendable phase change detector device for use in obtaining acooling curve of molten material according to claim 11 wherein saidbinder comprises a phenol-formaldehyde resin.

13. An expendable phase change detector device for use in obtaining acooling curve of molten material according to claim 10 wherein said wellstructure comprises a monolithic thin sand shell formed from a mixtureof sand and a phenol-formaldehyde resin binder.

14. An expendable phase change detector device for use in obtaining acooling curve of molten material according to claim 10 including a standfor supporting said device with the well structure thereof in verticalposition, said stand comprising a base having conduit means supportedthereby in substantially vertical position, electrical contact structuredisposed at the upper end of said conduit and adapted to cooperate withsaid plug-in contact structure-of said device while supporting saiddevice in substantially vertical position, and electrical conductorsconnected to the contacts of said stand, said electrical conductors ofsaid stand extending downwardly through said conduit and beingaccessible from said stand for connection to a measuring circuit.

15. An expendable phase change detector device for use in obtaining acooling curve of molten material outside of the inciting furnacecomprising well structure adapted for vertical disposition and having anopen end at the top thereof to permit said iwell structure to receiveand retain a molten material placed therein, temperature sensing meanssupported from the bottom of said well structure and extending apredetermined distance upwardly therefrom for disposition of aheat-responsive portion thereof substantially on the longitudinal axisof said well structure a substantial distance from the bottom of saidwell structure and spaced from the walls thereof, said well structurecomprising a monolithic mass of sand and a resin binder and tending toretard cooling at a rate that allows detection of the thermal arrests inaccordance with the rate of response of the temperature sensing means,said temperature sensing means having electrical conductors extendingthrough said bottom of said well and terminating in plug-in electricalContact structure, and said temperature sensing means having a lengthsuch that said heat-responsive portion of said temperature sensing meansis always completely surrounded by material placed in said Well andbelow any shrinkage cavity formed in said material upon cooling.

16. An expendable phase change prefribricated detector device for use inobtaining a cooling curve of molten material outside ofthe meltingfurnace comprising well structure having a volume of the order of tencubic inches or less and adapted for vertical disposition to hold asample of a molten material placed therein, temperature sensing meansextending through a wall of the well structure and permanently scaled toand supported by said well structure so as to become on integral partthereof for disposition of a heat responsive portion of said temperaturesensing means within said well structure and spaced from the wallsthereof, said well structure comprising a monolithic mass ofnon-metallic material molded into shape, open at one end, and free ofseams, said material of said `well structure tending to retard coolingof the molten material at a rate that allows detection of the thermalarrests of the molten material in accordance ywith the rate of responseof the temperature sensing means, said temperature sensing means havingelectrical conductors extending through the wall of said well structureand having a length such that said heat responsive portion of saidtemperature sensing means is always completely surrounded by thematerial placed in said well structure and below any shrinkage cavityformed in said material upon cooling, said electrical conductorsterminating in electrical Contact structures accessible exteriorly ofsaid well, said well structure having an extension projecting exteriorlyof the well adjacent tlze location where said electrical conductorsextend through said wall, said extension having means for holdin i saidContact structures in fixed positions of predetermined polarity forengagenient with associated Contact structures of corresponding polarityin connecting said temperature sensing means to a measuring circuit.

I7. An expendable phase change prefahricatcd detector device for use inobtaining a cooling curve of molten material outside of thc meltingfurnace comprising.' wel] structure adapted for vertical disposition tohold o sample o] n molten material plnccu' therein, tcfnpcrntnre sensingmeans extending throng/1 o woll of said wel! strncturc and permanentlysealed to (1nd supported by said well structure so as to become anintegral part thereof for disposition of a lient responsive portion ofsaid temperature sensing means wit/iin solo' ucll structure and spacci!from the walls thereof, said well structure comprising a monolithic massof non-metallic mote/inl molded into slirtpe, open at one end, and freeof scri/ns, .mid material of said well structure tending to retardcooling of thc molten material at a rate that allows detection of thetllcrnml arrests of the molten material in accordance with the rate ofresponse of the tempera/nrc sensing means, said temperature sensingnzcons haring electrical conductors extending throng/1 the will] ofsnit] well structure und haring a length snc/z that said /zcfitresponsive portion of said temperature sensing means is alwayscornpletely surrounded by the material placed in said well structure andbelow any shrinkage cavity fora-ted in said material upon cooling, saidelectrical conductors having a predetermined polarity and terminatingexternally of said well structure in bare electrical contact portionsspaced one from the other in predetermined orientation, a stand forsupporting said device, said stand comprising a base having means forsupporting said well structure in vertical position, tacts carried' bysaid stand, said pair of electrical contacts being xed on said stand andhaving a .spacing which corresponds to the spacing of said bareelectrical contact portions of said electrical conductors for effectingan electrical connection of proper polarity therebetween in connectingsaid temperature sensing means to a measuring circuit.

References Cited The following references, cited by the Examiner, are ofrecord in the patented le of this patent or the original patent.

UNITED STATES PATENTS 3,321,973 5/ 1967 Anderson. 2,464,487 3/1949Chappell 285-55 2,887,879 5/1959 Vonneqnt 73-204 and a pair of polarizedelectrical con- 1 10 2,970,719 2/1961 Brady 285--55 3,007,988 9/1961Jaffe et al. 73-359 3,048,642 8/1962 Parker 136-234 3,081,628 3/1963Salera 73--204 3,099,922 8/1963 Crocker 73-341 3,169,401 2/1965 Newman73-359 FOREIGN PATENTS 921,027 8/1960 Great Britain. 1,253,390 1/1961France.

801,604 1/ 1951 Germany.

OTHER REFERENCES Temperature, Its Measurement and Control in Science andIndustry: Edited by American Institutes of Physics. Published byReinhold Publishing Corporation (1941). Pages 974-983 relied on.

Redshaw, H. A., et al.: Gray Cast Iron Control by Cooling CurveTechniques, in Modern Castings, vol. 41, No. 2, February 1962, TS 200A7, page 95.

Modern Castings, wol. 4l, No. 3, March 1962, pages 37-39, TS 200 A7.

DAVID SCHONBERG, Primary Examiner. LOUIS R. PRINCE, Examiner. FREDERICKSHOON, Assistant Examiner.

